The Occupational Safety and Health Administration (OSHA) requires a handrail for stairways with more than four stairs. The International Building Code also outlines handrail requirements for stairs in any structure. Handrails are required on one side of the residential stairways, and must be at least 1½ inch from the wall and 34 to 38 inches tall, according to the International Building Codes. Newel posts secured to the floor or stairs on each end of the staircase provide the strength and stability of any stair railing system, and balusters prevent anyone from falling through the stairs and the rail.
Measure the height for your newel post with a measuring tape and cut the posts with the mitre saw. If you are replacing an existing railing system, you can use the old posts as a guide for your height measurement. All of your posts will be the same height. The newel is the decorative post at the top and bottom of the stair rail system.
Notch both newels. Your newels should sit ½ on the stair and ½ off of it and onto the front of the stair. The newel should sit comfortably on the top of the stair beneath the top stair. Notch the post with your hand saw to ensure you get a snug fit. You want your newel to fit as close as possible to the stair, because it will be bolted into the front of the stair.
Drill holes into the post and into the front of the top stair where the post will sit. Use a wood drill bit the size of the bolt, but that will drill a slightly larger hole on the outside so the bolt will sink into the newel and become less visible. The wood bit has a point on the end and flappers just beyond the point. Measure your holes carefully so that you drill in the right place.
Position the newel into place and secure it with lag bolts to the front of the top stair. Continue steps 2 through 4 on the bottom newel. Use the level to ensure the newels are standing straight and are tightly bolted into the stair.
Position your railing up next to your newels once they are installed. Rest the railing on the stair and mark the back of the railing to determine the length and angles you at which you need to cut the rail. Use a pencil to mark these angles.
Cut your rail with a mitre saw. The angle should be 45 degrees, but watch your markings closely to ensure your rail fits properly. Measure and cut your balusters at the same angle on the top to ensure they will be positioned properly. Balusters are the smaller, decorative posts that go between the stairs and the railing.
Drill holes into the stairs that where the balusters will go. Use your rail as a guide for spacing your balusters, and measure exactly where each hole needs to be. Use a drill bit the exact size of the baluster screw, using the stair drill bit.
Drill a hole into the bottom of the baluster and place the baluster bolt inside. Secure the bolt inside the hole. Screw the first baluster into the first hole in the stairs.
Attach the handrail to the newels, using rail fasteners. Insert the balusters into the railing; secure them with wood glue and a finish nail on either side. Use the level to ensure your balusters are straight. Tighten your newels and all your other screws and bolts.
Secure every joint with wood glue to ensure strength and durability of your railing. Have a friend help you install railings and newels to make the process much simpler. Measure everything twice before cutting anything to ensure your cutting is correct.
Wear safety gear when using any type of power tool, especially saws.